School-age children with undetected and unremediated health and developmental problems are a major concern. This research addresses this problem through a longitudinal study to increase knowledge about the etiology of these problems and through the development of screening and assessment methods for the early identification of high-risk groups. The focus of the study and the assessment methods is the home environment and ways in which nurses can provide preventive care before the developmental problems progress to school-age dysfunction in learning and behavior. The data collected will be from a cohort of children at age three and four years. The information is critical to validating the predictiveness of the parent, child and environmental assessments made on these same children from birth through two years of age in an earlier study phase.